Syringe for injecting small measured volumes of liquid



l. s. HoRABlN 3,203,455

2 Sheets-Sheet 1 MSM JW .B7 fr Aug. 3l, 1965 SYRINGE FOR INJEGTING SMALL MEASURED VOLUMES 0F LIQUID Filed Feb. 5, 1962 L S. HORABIN Aug. 3l, 1965 SYRINGEFOR INJECTING SMALL MEASURED VOLUMES OF LIQUID Filed Feb. 5, 1962 2 Sheets-Sheet 2 MMM/0MM By 6MM/bv 4 W United States Patent O M 3,293,455 SYRiNGE FOR INXECTENG SMALL MEASURED VLUMES F LHQUED ivan Samuel Horabn, South Beni-lect, Essex, England, assigner to Marryat @e Place Limited, London, England, a corporation of the United Kingdom Filed Feb. 5, 1962, Ser. No. 171,155 Claims priority, application Great Britain, Feb. 2i), 1961,

i4 ciaims. (ci. 141-329) This invention relates to syringes and has for its object a syringe capable of injecting small volumes of of liquid.

In modern gas chromatography apparatus it is a requirement to introduce small sample quantities ofliquid into the chromatograph of the order of one microlitre or even less.

While existing syringes make use of the bore of a small bore steel needle as the barrel of the syringe and a Wire travelling the full length of the needle forms the plunger, this system suffers the disadvantage that it is virtually impossible to discover whether the bore of the needle is full of liquid. Injection of reproducible quantities depends on the needle being full of liquid without air bubbles. An object of the present invention is to lovercome this objection.

According to the present invention a syringe for injecting small volumes of liquid comprises a tubular member attached to one end of which is a needle, the needle and the tubular member having axially aligned bores Within which a iirst plunger is slidably mounted, and a second plunger element for propelling liquid from the tubular member into the needle, by means of which it can be lled when the rst plunger has been withdrawn and whereby a predetermined amount of liquid can be expelled from the syringe by discharging the liquid content of the needle or a known quantity thereof.

According to a further feature of the present invention a syringe comprises a needle the bore of which may be up to 1/32" diameter and forms the barrel of the syringe and in which slides a plunger so supported that it may readily be withdrawn from and re-inserted into the bore of the needle, such supporting being achieved by attaching the needle to a co-axia1 tubular member in which is interchangeably mounted a guide tube for the plunger.

The invention is illustrated in the accompanying drawings in which:

FIGURE 1 is a diagrammatic View of a syringe constructed in accordance with one embodiment of the invention;

FIGURE 2 is a section corresponding to FIGURE 1 showing a syringe having a second plunger in a separate cylinder; v

FIGURE 3 is a sectional view of la syringe constructed in accordance with a preferred embodiment of the invention;

FIGURE 4 is an enlarged view of part of the syringe shown in FIGURE 3.

Referring first to FIGURE 1 .of the drawings, the syringe of this invention comprises a cylinder block 1 having Ia bore 2 in which is secured at one end a tubular structure or member 3, while in its other end is slidably mounted a part 4, both the tubular member 3 and part 4 being formed with an axial bore 6 to receive a plunger 7, iixed to the part 4, the plunger 7 being referred to hereinafter as the second plunger element.

The needle of the syringe, which is indicated at 10, is formed with a small capillary passage or bore, within which is fitted a plunger 11, this being referred to as the first plunger. It will be seen that the rst plunger 11 extends through the needle 10 and the larger secondary p 3,203,455 Patented Aug. 31, 1965 ICC plunger 7 and is secured at its other end to an end piece or handle 12., by which it may be withdrawn and advanced when forcing out a measured amount of liquid in the needle.

In the tubular structure or member 3 are two lateral openings in which are inserted short lengths of tube 14, 14 forming inlet and outlet passage means by which a sample of liquid can be introduced into the syringe, the needle 11i terminating short of the tubes 14, 14 so as to provide a portion in the tubular member 3 serving as a loading chamber indicated at 15.

In operation, to load the bore of the needle 10 with liquid, the second plunger element 7 is withdrawn by gripping the projecting end of part 4 and pulling it outwardly in the direction of arrow X so as to open up a gap between the inner end of plunger 7 and the end of needle 10. This allows the sample liquid to flow in through the tube 14 which is connected to a source of liquid supply, excess liquid passing out through tube 14', carrying with it any air present in the tubular member 3. The tubes 14, 14 are constructed of translucent material so that the operator can observe when all air bubbles have been excluded: Having iilled the tubular structure bore portion or loading chamber 15 with liquid, the main or iirst plunger 11 of the syringe is Withdrawn by pulling end piece 12 in the same direction as arrow X until the end of the plunger 11 is clear of the bore of needle 1t): By forcing part 4 axially inwards, it will displace the second plunger element 7 which in turn, after passing and cutting oii dow through the tubes 14, 14 will force liquid in chamber 15 into the bore 40f needle 10: Surplus liquid is now removed from the point of the needle which can then be introduced through the membrane of a chromatograph: The final step is to advance the iirst plunger 11 to the limit of its travel to force out the amount (predetermined) of liquid in the bore of needle 10.

Referring now to FIGURE 2, the member 3 is fitted with a single inlet tube 14 which is connected through `a length of flexible translucent tube 16 to a connector 17 forming part of a larger syringe including a cylinder 18 and plunger 19, the plunger 19 in this case operating as the secondary plunger clement and being used to introduce sample liquid into the tubular structure` bore portion or loading chamber 15 and needle 10.

The sequence of operations remains the same except that the part 4 and the second plunger element 7 are not withdrawn in order to ll the loading chamber 1S with liquid. Should bubbles exist in the tube 16, the sample liquid may be drawn into the cylinder 18, the whole syringe turned so that the needle 1i) points upwards, and then, by advancing the plunger element 19, the air may be expelled and the translucent tube 43 Iilled with bubble free liquid.

For convenience the discharge end of the cylinder 11i is provided with a conical nose 18 by which it is detachably connected to the connector 17.

Referring now to FIGURE 3, which shows a preferred embodiment of the invention, the syringe comprises a cylinder block 20, e.g. of aluminum in which are parallel bores, the larger one accommodating the secondary plunger element and the smaller one a fixed part 23 having a bore into which the main plunger 11 can be Withdrawn. Within the larger bore is a steel sleeve 21 constituting the cylinder of a larger auxiliary syringe, the plunger of which is indicated at 22 and forms the second plunger element.

Secured Within the second and smaller bore in the cylinder block 2t) is a xed part 23. The fixed part 23 is formed at one end with a capillary passage 24 for the main plunger 11 and has a counterbore 25 in which is slidably mounted a support tube 26 having an axial bore of the same diameter as the capillary bore 24 for the first plunger 11.

The part 23 has a threaded portion 23 to receive a cap 23 in which is inserted one end of a small diameter tube 30, referred to hereinafter as the guide tube, and having a bore 31 of the same diameter as the bore in the needle 10. Between the portion 23' and the cap 28 is a sealing washer 40'.

The guide tube 30 is welded at its inner end to cap 28. The outer end of tube 30 projects through the double spigotted end piece indicated at 32, and into the counterbore of a tubular member 37. The double spigot piece 32 includes two threaded spigots 33, 34 separated by a central shoulder or flange 32. The spigot 33 is screwed to a threaded counterbore in a projection 20 of the cylinder block 20. The other spigot end 34 of the spigot piece 32 is provided with an apertured end cap 36, by means of which the tubular structure comprising the guide tube 30 and the member 37 is held in position, the member 37 for this purpose being provided with a flange 39 for engagement with the cap 36.

Mounted between the end of member 37 and the end of a counterbore in the piece 32 is a sealing ring 40. The guide tube 30 is thus sealed against leakage by the compression of sealing ring 40 between tubular member 37 Vand the inner shoulder in spigot 32. The liquid seal of plunger 11 within the bore of guide tube 30 is achieved by the compression of the sealing ring 40 between the threaded end 23' and the cap 28. The needle 10 is welded at 41 at its point of entry to the tubular member 37.

A branch tube 42 on the tubular member 37, and also welded thereto, is connected through a translucent tube 43 to a stainless steel nozzle 44 secured to a plug 45 by which the cylinder insert 21 of the auxiliary syringe is fixed within the cylinder block 20.

It will be seen therefore that any possible leakage from the inner end of the needle from the guide tube 30 and from the interface f plunger 11 and the bore of guide tube 30 is eliminated by the sealing rings 40 and 40 and by the action of the second plunger element in respect of leakage through the branch tube 42.

In the fully advanced position, eg., as found on completion of the injection of a sample, the first plunger 11 extends from the tip of the needle through guide tube 30, through the capillary passage in the threaded end 23 of part 23 and through the sliding support tube 26 to its outer end where it is secured by the grub screw 54 in knob 50, the grub screw entering member 26 through a side hole and clamping the end of plunger 11 against the inner wall of element 26.

To load the bore of the needle 10 with liquid, the first step is to withdraw the first plunger 11 by withdrawing knob S0, this movement being continued until the plunger 11 is clear of the bore of needle 1f), and the end of the plunger 11 is to the right of the branch tube 42, as viewed in FIGURES 3 and 4. The tip of the needle in then inserted in the sample liquid and by means of the auxiliary syringe, sample liquid is drawn up the needle and into the translucent tube 43. Should bubbles exist in tube 43 the sample liquid may be drawn into the cylinder of the second plunger element 22, the needle removed from the sample liquid, the whole syringe turned s0 that the needle points upwards and then, by advancing second plunger element 22, the air may be expelled and the translucent tube 43 filled with bubble free liquid.

The second plunger element 22 is now depressed to force the liquid back through the translucent tube 43 when it can again be inspected, movement of the second plunger element 22 being continued until a drop of liquid appears at the end of the needle 10, when it will be understood that needle 10 is full of liquid. The main plunger 11 is now advand by depressing the knob 50, this movement being continued until the plunger 11 is in the position within the needle corresponding to the required amount of liquid. Surplus liquid is now wiped 4 from the point of the needle 10 when the latter is introduced through the injection membrane, the plunger 11 being advanced until the limit of its travel, i.e. when knob 50 engages the end of insert 23.

The advantages `of this syringe are:

(l) The needle can be filled with liquid free from air bubbles.

(2) The syringe does not depend for its operation upon a close fit between the bore of the needle 10 and the first plunger 11 so that its performance is not affected by the normal wear of the first plunger due to abrasion between the plunger and the bore of the needle.

(3) The syringe contains no glass and is of robust construction.

(4) Should the needle 10 be broken, it is easily replaced. Also the wire plunger 11 is readily replaced when necessary.

Furthermore the possibility of withdrawing the plunger 11 from the bore of the needle 10 permits the bore of the needle to be loaded with sample liquid through its inner end (as opposed to the usual method of loading through the needle tip) by introducing the sample liquid through a branch tube 42 in the tubular member 37.

To .assist in dispensing a measured quantity of liquid, the syringe may be fitted with a calibration device to limit the travel of the needle. This consists of a spindle 51, on which is adjustably carried a sleeve 52 fitted with a latch arm 53 which can be moved into and out of the path of the knob 50 to restrict the movement of the latter.

What is claimed is:

1. In a syringe for injecting small measured volumes of liquid, the combination of a tubular structure having a bore; a needle having a small bore coaxial with said tubular structure bore, the inner end of said needle being fixed with `respect to said tubular structure and the inner end of said needle bore being communicable with the adjacent end of said tubular structure bore; means providing an inlet .passage opening laterally of said bores into the portion of said tubular structure bore adjacent said inner end of said needle for introducing fluid into said tubular structure bore portion adjacent to the inner end of said needle, a first plunger element mounted to move axially in said bores and being withdrawable from said needle bore to place the inner end of said needle bore into communication with said tubular structure bore portion and being projectable .into the needle bore for ejecting liquid therefrom; and means including a second plunger element operable independently of said first plunger element for enabling filling said tubular structure bore portion with liquid, said second plunger element being also operable independently of said first plunger element for discharging liquid through and from said tubular structure bore portion .to thereby remove from said tubular structure bore portion any liquid which may contain bubbles so that when said first plunger element is subsequently -projected into said needle bore only substantially bubble free liquid will be ejected therefrom.

2. Syringe according to claim 1 further including means providing an outlet passage opening into said tubular structure bore portion.

3. Syringe according to claim 2 in which the means respectively providing .said inlet passage and said outlet passage comprise translucent tubes whereby the presence of -air bubbles may be detected.

4. Syringe according to claim 1 including a cylinder block xed to said tubular structure at the end thereof remote from said needle and having a bore coaxial with said needle and tubular str-ucture bores; a par-t slidable in the bore in said cylinder block .and projecting from that end of the cylinder block remote from said needle, said second plunger element being fixed to the end of said part adjacent said `tubular structure, both said part and said second plunger element having bores coaxial with said needle bore and through which said first plunger element extends; and an end piece connected to said iirst plunger element at the end thereof remote from said needle and projecting beyond the end of said part remote from said needle, said first plunger element being operable by said end piece and said second plunger element being operable by said part.

5. Syringe according to claim 1 including a cylinder block having a bore coaxial with said needle; a part xed .in said cylinder barrel bore remote from said needle and having a bore coaxial with said needle, said tubular structure comprising a guide tube secured to said part, said first plunger element extending through the bores in said guide tube and said part; and an end piece connected to said irst plunger element at the end thereof remote from said needle.

6. Syringe according to claim 5 in which said cylinder block has a second bore providing a cylinder in which said second plunger element is operable.

'7. Syringe according to claim 6 in which said tubular structure is detachably secured to said cylinder block and said end piece comprises a support tube mounted to slide in said part and within which support tube said irst plunger element is detachably secured.

8. Syringe according to claim '7 including an end cap having a bore at one end receiving said tubular structure and having a counterbore at its other end; and a spigotted end piece attached to said cylinder block and having a spigot facing said needle and received in said end cap counterbore, said spigotted end piece having a bore receiving said tubular structure.

9. Syringe according to claim 6 in which said tubular structure comprises a tubular member having a bore at one end receiving said needle and a counterbore at its other end in which a part of said guide tube is received, said guide tube being of the same internal diameter as said needle and extending between said needle and said part and being coaxial therewith .to provide a continuous bore for receiving said iirst plunger element.

10. Syringe according to claim 1 in which said tubular structure comprises a tubular member, and a guide tube eoaxially received in said tubular member and having a bore in which said iirst plunger element is reciprocable, said inlet passage means being connected to said guide tube at a point within said .tubular member.

11. Syringe according to claim 5 including a threaded portion at the inner end of said part; a cap tted over said threaded port-ion and having an aperture through which said guide tube extends, said lcap securing said guide tube to said part; .and sealing means between the end of said guide tube and said cap.

12. Syringe according to claim 11 in which said tubular structure includes a tubular member in which said guide tube is received and in which the end of said cylinder block nearest said needle has a threaded counterbore, said syringe further comprising a ydouble spigotted end piece having a bore receiving said guide tube, one spigot of said end piece having threaded engagement with said threaded counterbore in said cylinder block and the other spigot of said end piece having a counterbore receiving said tubular member, said tubular member being releasably secured to said end piece.

13. Syringe according to claim 12, including a sealing ring between the end of said tubular member remote from said needle and said counterbore in said other spigot of said end piece.

14. Syringe according to claim 2 in which said outlet passage is constituted by said needle bore.

References Cited bythe Examiner UNITED STATES PATENTS 1,951,503 3/34 Creveling 222-256 XR 2,064,815 12/36 Armstrong 141-329 XR 2,414,911 1/47 Temple 222-81 2,570,787 10/ 51 Gammeter 141-3 29 XR LAVERNE D. GEIGER, Primary Examiner. 

1. IN A SYRINGE FOR INJECTING SMALL MEASURED VOLUMES OF LIQUID, THE COMBINATION OF A TUBULAR STRUCTURE HAVING A BORE; A NEEDLE HAVING A SMALL BORE COAXIAL WITH SAID TUBULAR STRUCTURE BORE, THE INNER END OF SAID NEEDLE BEING FIXED WITH RESPECT TO SAID TUBULAR STRUCTURE AND THE INNER END OF SAID NEEDLE BORE BEING COMMUNICABLE WITH THE ADJACENT END OF SAID TUBULAR STRUCTURE BORE; MEANS PROVIDING AN INLET PASSAGE OPENING LATERALLY OF SAID BORES INTO THE PORTION OF SAID TUBULAR STRUCTURE BORE ADJACENT SAID INNER END OF SAID NEEDLE FOR INTRODUCING FLUID INTO SAID TUBULAR STRUCTURE BORE PORTION ADJACENT TO THE INNER END OF SAID NEEDLE, A FIRST PLUNGER ELEMENT MOUNTED TO MOVE AXIALLY IN SAID BORES AND BEING WITHDRAWABLE FROM SAID NEEDLE BORE TO PLACE THE INNER END OF SAID NEEDLE BORE INTO COMMUNICATION WITH SAID TUBULAR STRUCTURE BORE PORTION AND BEING PROJECTABLE INTO THE NEEDLE BORE FOR EJECTING LIQUID THEREFROM; AND MEANS INCLUDING A SECOND PLUNGER ELEMENT OPERABLE INDEPENDENTLY OF SAID FIRST PLUNGER ELEMENT FOR ENABLING FILLING SAID TUBULAR STRUCTURE BORE PORTION WITH LIQUID, SAID SECOND PLUNGER ELEMENT BEING ALSO OPERABLE INDEPENDENTLY OF SAID FIRST PLUNGER ELEMENT FOR DISCHARGING LIQUID THROUGH AND FROM SAID TUBULAR STRUCTURE BORE PORTIO NTO THEREBY REMOVE FROM SAID TUBULAR STRUCTURE BORE PORTION ANY LIQUID WHICH MAY CONTAIN BUBBLES SO THAT WHEN SAID FIRST PLUNGER ELEMENT IS SUBSEQUENTLY PROJECTED INTO SAID NEEDLE BORE ONLY SUBSTANTIALLY BUBBLE FREE LIQUID WILL BE EJECTED THEREFROM. 